Brake pedal was very stiff

JEREMY0507

MEMBER
1995 GMC SIERRA
5.7L
V8
4WD
AUTOMATIC
200,000 MILES

So my brake pedal was very stiff an my truck was barely stopping so I changed the brake booster. The issue has not changed. It is still hard and my engine idles higher when I push brake pedal which it did before also. Think I got a faulty booster or maybe another issue?

6 Replies

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi and thanks for using 2CarPros.com. If it is doing the same thing, it does not sound like a booster problem. For the booster to operate properly, it needs eighteen inches of vacuum from the engine. Remove the vacuum hose to the booster and check if you are getting that. If you are not suspect there is a plug in the hose, a cracked hose, or another vacuum leak causing engine vacuum to drop.

Here are directions for checking engine vacuum and how to identify a leak:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Try this first and let me know what you find.

Take care,

Joe

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Wednesday, April 14th, 2021 AT 1:47 PM

JEREMY0507

MEMBER
27 POSTS

Will a vacuum leak cause the brake pedal to get very hard an not let the vehicle stop?

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Wednesday, April 14th, 2021 AT 1:47 PM

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi again. The reason the pedal is normally easy to press is because of engine vacuum in the brake booster. If there is a leak, you may not get the assist. Hence, it is hard to press.

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Wednesday, April 14th, 2021 AT 1:47 PM

JEREMY0507